Assembled battery and vehicle provided with same

ABSTRACT

Provided is a highly reliable assembled battery having a high cooling efficiency. An assembled battery in which first passages formed between a rectangular cell and one surface of the body part of a separator, and second passages formed between other rectangular cell and the other surface of the body part of the separator are provided in an alternating manner from above to below. Openings are provided in a side wall part of the separator. The first passages and the second passages are exposed by the openings.

TECHNICAL FIELD

The present invention relates to an assembled battery where a pluralityof rectangular battery cells are stacked through separators, and avehicle including the same.

BACKGROUND ART

Conventionally, in a hybrid vehicle or an electric vehicle havingdriving source of electric power, an assembled battery where anplurality of rectangular battery cells are connected in series orparallel, is used.

In the assembled battery, a separator is disposed between adjacentrectangular battery cells. This separator plays a role to preventrectangular battery cells from directly contacting each other.Additionally, projections and depressions are formed on the separator,and thus passage for cooling gas flowing between the rectangular batterycell and the separator are formed. Then, when the rectangular batterycell generates heat, the rectangular battery cell can be cooled bymaking the cooling gas flow through the passage.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Laid-Open Patent Publication No.2013-004523.

Patent Literature 1 discloses the following. The projection is providedat the base part of the cell barrier (separator), a passage where heatexchange medium passes, is provided between the cell barrier and thebattery cell. Further, the cell barrier has the flange part, an openingis provided at the flange part.

SUMMARY OF THE INVENTION Technical Problem

In an assembled battery which in used in a hybrid vehicle or an electricvehicle, it is necessary to prevent that the assembled battery isdamaged and then the abnormality of the rectangular battery cellhappens, even when the vehicle is damaged by a car accident and a strongimpact is exerted on the assembled battery. An object of the presentinvention is to provide an assembled battery where a cooling performanceof a rectangular battery cell is maintained and a high reliability isobtained.

Solution to Problem

According to an assembled battery in one aspect of the presentinvention, an assembled battery comprises: a pair of end plates; and aplurality of rectangular battery cells stacked through separators,between the pair of the end plates, interposing.

Each of the rectangular battery cells has a bottom surface, a pair oflarge area side surfaces, and a small area side surface, and then eachof the separators has a body part and a pair of side wall parts providedat both ends in a width direction of the body part, and then the bodypart is disposed between adjacent battery cells of the rectangularbattery cells.

The body part has vertical portions vertically extending in analternating manner from above to below and a horizontal portionhorizontally extending, and an end part of each of the vertical portionsis connected to an end part of the horizontal portion.

A first passage where heat exchange gas passes, is formed between onesurface of the body part of each of the separators and one adjacentbattery cell of the rectangular battery cells, and then a second passagewhere heat exchange gas passes, is formed between other surface of thebody part of each of the separators and other adjacent battery cell ofthe rectangular battery cells, and then the first passage and the secondpassage are provided in an alternating manner from above to below.

The side wall parts of each of the separators are disposed so as to facethe small area side surfaces of the adjacent two rectangular batterycells, and then each of the side wall parts has an opening, and then atleast one of the first passage and the second passage are exposedthrough the opening.

Advantageous Effects of Invention

According to an assembled battery in one aspect of the presentinvention, the small area side surface of the rectangular battery cellcan be covered with the side wall parts of the separators. Therefore, itis prevented that the impact is exerted directly on the rectangularbattery cell, even when a strong impact is exerted on the assembledbattery by a car accident. It is effectively prevented that the smallarea side surface of the rectangular battery cell is damaged or brokenby components constituting the assembled battery or the vehicle by a caraccident and the abnormality of the rectangular battery cell happens.

According to an assembled battery in one aspect of the presentinvention, passages through which heat exchange gas flows between theseparator and the rectangular battery, are formed. Then, the passagesare exposed through openings provided at the side wall part of theseparator. Therefore, since the heat exchange gas is made flow into thepassages, the rectangular battery cells are effectively cooled. Further,the body part of the separator has corrugate part where the verticalportions and the horizontal portions are provided in the alternatingmanner. The width (a distance between the body part of the separator andthe large area side surface of the rectangular battery cell) of thepassage of the heat exchange gas is can be larger than that of acomparison of FIG. 12. As a comparison, it is assumed that projectionparts are formed at both surfaces of a body part as shown in FIG. 12.Thus, the heat exchange gas flows into the passage smoothly, and flowsinside the passage smoothly, and then the rectangular battery cell canbe effectively cooled. Therefore, according to an assembled battery inone aspect of the present invention, the assembled battery has a highcooling performance of the rectangular battery cell, and a highreliability. Here, “a vertical direction” in this description, means adirection perpendicular to the bottom surface of the rectangular batterycell, and “a horizontal direction” means a direction in parallel withthe bottom surface of the rectangular battery cell.

In the present invention, one or more of openings may be provided at theside wall part. When the one opening is provided at the side wall part,the first passage and the second passage are exposed through this oneopening. However, it is preferable that a plurality of the openings areprovided at the side wall part. In this case, the first passage and thesecond passage are exposed through one of the openings. Otherwise, thefirst passage or the second passage is exposed through one of theopenings. The opening through which the first passage is exposed, andthe opening through which the second passage is exposed, may be providedrespectively.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a rectangular battery cell used in anassembled battery relating to an embodiment.

FIG. 2 is a perspective view of the assembled battery relating to theembodiment.

FIG. 3A is a side view of the assembled battery relating to theembodiment. FIG. 3B is a plan view of the assembled battery relating tothe embodiment.

FIG. 4 is a perspective view of a separator used in the assembledbattery relating to the embodiment.

FIG. 5A is a front view of the separator. FIG. 5B is a left side view ofthe separator. FIG. 5C is a right side view of the separator.

FIG. 6A is a sectional view along a line VI-VI in FIG. 5A. FIG. 6B is anenlarged view of FIG. 6A.

FIG. 7 is a sectional view along a line in FIG. 3B.

FIG. 8 is an enlarged view of a VIII portion in FIG. 7.

FIG. 9A is a sectional view along a line IXA-IXA in FIG. 8. FIG. 9B is asectional view along a line IXB-IXB in FIG. 8.

FIG. 10 is an enlarged view of a X portion in FIG. 3A.

FIG. 11A is a sectional view along a line XI-XI in FIG. 5A. FIG. 11B isan enlarged view in a vicinity of a bottom part.

FIG. 12 is a view showing a separator of which projection parts areformed at both surfaces of a body part.

FIG. 13 is an enlarged view in a vicinity of an opening of FIG. 9B.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to figures. However, the embodiments describedbelow are illustrative examples for embodying the technical spirit ofthe present invention, are not intended to limit the present inventionto the embodiments.

FIG. 1 is a perspective view of rectangular battery cell 1 used inassembled battery 10 relating to an embodiment. Rectangular battery cell1 has rectangular outer case 2 (having a rectangular parallelepipedshape) made of metal such as aluminum. In rectangular battery cell 1, anelectrode assembly including a positive electrode plate and a negativeelectrode plate is stored in outer case 2 with an electrolyte.Rectangular outer case 2 has a rectangular piped shape having a bottompart, including a pair of large area side surface 2 a, a pair of smallarea side surface 2 b, and bottom surface 2 c. An opening of rectangularouter case 2 is sealed by sealing plate 3. Positive terminal 4 andnegative terminal 5 are provided at sealing plate 3. Positive terminal 4is electrically connected to the positive electrode plate, and negativeterminal 5 is connected to the negative electrode plate. Insulationmembers 6, 7 made of resin, are respectively interposed between positiveterminal 4 and sealing plate 3, between negative terminal 5 and sealingplate 3. Gas exhaust valve 8 is provided at sealing plate 3. Gas exhaustvalve 8 is broken when the inner pressure of rectangular outer case 2becomes the preset value or more, and then gas inside rectangular outercase 2 is exhausted outside through gas exhaust valve 8. An injectionhole for injecting the electrolyte is provided. After injecting, thisinjection hole is sealed by sealing plug 9. Here, as rectangular batterycell 1, it is preferable to use a non-aqueous electrolyte secondary cellsuch as a lithium ion secondary battery cell.

As shown in FIG. 2, FIG. 3A, and FIG. 3B, in assembled battery 10, aplurality of rectangular battery cells 1 are stacked through separators12, between a pair of end plates 11. Binding bars 13 are respectivelyconnected to the pair of end plates 11, and thus the stacked pluralityof rectangular battery cells 1 are bound by the pair of end plates 11and binding bars 13. Main parts 13 a of binding bars 13 are respectivelydisposed at side surfaces of assembled battery 10. Openings 13 c areprovided at main part 13 a of binding bar 13. Positive terminals 4 andnegative terminals 5 of adjacent rectangular battery cells 1 areelectrically connected by bus-bars 14. Adjacent rectangular batterycells 1 are disposed such that large area side surfaces 2 a thereoffaces each other through separators 12. Separator 12 has body part 12 a,and then this body part 12 a is disposed between adjacent rectangularbattery cells 1. Accordingly, one surface of body part 12 a faces largearea side surface 2 a of one rectangular battery cell 1, and othersurface of body part 12 a faces large area side surface 2 a of otherrectangular battery cell 1.

As shown in FIG. 4, FIGS. 5A to C, FIG. 6A, and FIG. 6B, separator 12has body part 12 a, side wall parts 12 b, bottom part 12 c, and upperwall part 12 d.

Body part 12 a of separator 12 has corrugate part. The corrugate parthas vertical portions 12 a ₁ vertically extending, and horizontalportions 12 a ₂ horizontally extending, in an alternating manner fromabove to below. Vertical portion 12 a ₁ has a roughly rectangular shape,and its long side extends in a width direction of body part 12 a. Then,vertical portions 12 a ₁ are disposed so as to face large area sidesurface 2 a of rectangular battery cell 1 through an insulation sheet orthe like. Horizontal portion 12 a ₂ is disposed so as to couple verticalportion 12 a ₁ located above and vertical portion 12 a ₁ located below.One end part of horizontal portion 12 a ₂ is connected to the low endpart of vertical portion 12 a ₁, and other end part of horizontalportion 12 a ₂ is connected to the upper end part of vertical portion 12a ₁ located below. Thus, in the one surface of body part 12 a, aplurality of recess parts 18 extending in the width direction of bodypart 12, are provided at intervals. Then, by recess parts 18, spacesextending in the width direction of body part 12 a between body part 12a and rectangular battery cell 1 are formed. Those spaces are passage 16of heat exchange gas. Regions where the spaces are formed by recess part18, and regions where no space is formed by contacting body parts 12 aand rectangular battery cell 1, are formed in an alternating manner fromabove to below. Also, in the other surface of body part 12 a, aplurality of recess parts 18 extending in the width direction of bodypart 12, are provided at intervals. Here, recess parts 18 in the othersurface of body part 12 a corresponds to the regions where no space isformed by contacting body parts 12 a and rectangular battery cell 1 inthe one surface of body part 12 a.

As shown in FIG. 7 and FIG. 8, the passages (first passages 16 a) of theheat exchange gas formed at the one surface side of body part 12 a, andthe passages (second passages 16 b) of the heat exchange gas formed atthe other surface side of body part 12 a, are formed in an alternatingmanner from above to below.

As body part 12 a of separator 12 has such a shape, the width (adistance between body part 12 a and large area side surface 2 a ofrectangular battery cell 1) in each of passage 16 is larger than that ofa comparison of FIG. 12, when the intervals of rectangular battery cells1 are equal. As a comparison, it is assumed that projection parts 20 areformed at both surfaces of body part 12 a as shown in FIG. 12. Thus, theheat exchange gas easily flows into passages 16. Additionally, the heatexchange gas easily flows through passages 16. Accordingly, rectangularbattery cells 1 are efficiently cooled. Since first passage 16 a andsecond passage 16 b are formed in the alternating manner from above tobelow, both surfaces of rectangular battery cell 1 are cooled equally.

As shown in FIG. 6B, preferably, thickness T2 in the vertical directionof horizontal portion 12 a ₂ is larger than thickness T1 in thehorizontal direction of vertical portion 12 a ₁. Thus, the width ofpassage 16 is made wide, and also the strength of body part 12 a can bemade high. Therefore, when rectangular battery cells 1 are swollen bycharge and discharge and separators 12 are pressed, it is surelyprevented that passages 16 of the heat exchange gas are crushed by largedeformation of separators 12. Further, body part openings 17 are formedat end parts in the width direction of body part 12 a. As body partopenings 17 are formed, the heat exchange gas smoothly flows intopassages 16, pressure loss can be suppressed.

As shown in FIG. 4 and FIG. 5, a pair of side wall parts 12 b are formedat both ends in the width direction of body part 12 a of separator 12.Side wall parts 12 b are disposed so as to extend in the stackeddirection of rectangular battery cells 1. Side wall part 12 b has firstregion 12 b ₁ projecting from body part 12 a to the one side in thestacked direction of rectangular battery cell 1, and second region 12 b₂ projecting from body part 12 a to the other side. First region 12 b ₁is disposed so as to face small area side surface 2 b of rectangularbattery cell 1 (the first rectangular battery cell) located at the onesurface side of body part 12 a. Additionally, second region 12 b ₂ isdisposed so as to face small area side surface 2 b of rectangularbattery cell 1 (the second rectangular battery cell) located at theother surface side of body part 12 a. Preferably, end parts of side wallpart 12 b of separator 12, contacts end parts of side wall part 12 b ofadjacent separator 12. Side wall part 12 b of separator 12 is made ofthe same material as body part 12 a. Preferably, in side wall part 12 bof separator 12, the end part which contacts the end part of side wallpart 12 b of adjacent separator 12 is also made of the same material asbody part 12 a.

Opening 15 is provided at side wall part 12 b of separator 12. Thisopening 15 is formed so as to extend in first regions 12 b ₁ and secondregions 12 b ₂. Opening 15 is formed so as to couple the outer side ofside wall part 12 b and passage 16. As shown in FIG. 9A and FIG. 9B,opening 15 which is provided at one end side of side wall part 12 b inthe width direction of body part 12 a, passage 16 a or 16 b, and opening15 which is provided at other end side of side wall part 12 b in thewidth direction of body part 12 a, are connected with consecutive space.Thus, the heat exchange gas is made flow into passage 16 from opening 15at the one end side, and then the heat exchange gas is exhausted fromopening 15 at the other end side.

Preferably, both of small area side surface 2 b of first rectangularbattery cell 1 and small area side surface 2 b of second rectangularbattery cell 1, are exposed from one opening 15. When gas flows from awide space to a narrow space, a seed of the gas changes. Then the morerapidly a cross sectional area of a passage through which the gas flowschanges, the more largely a speed of the gas changes. Then, it may bedifficult that the gas smoothly flows. In contrast, when both of smallarea side surface 2 b of first rectangular battery cell 1 and small areaside surface 2 b of second rectangular battery cell 1 are exposed fromone opening 15, as shown in FIG. 13, the cross sectional area of thepassage 16 through which the gas flows, can gradually become small.Therefore, in this structure, the heat exchange gas can smoothly flowwithout the gas speed largely changing. As shown in FIG. 13, inrectangular outer case 2 of rectangular battery cell 1, preferably, arounded part is formed in a portion which connects large area sidesurface 2 a and small area side surface 2 b. Thus, the cross sectionalarea of the passage through which the gas flows, can be made changesmoothly from opening 15 to passage 16.

A plurality of openings 15 are arranged in one row vertically at sidewall part 12 b. Then, as shown in FIG. 10, openings 15 communicatingwith first passages 16 a and openings 15 communicating with secondpassages 16 b are arranged in an alternating manner from above to below.Thus, rectangular battery cell 1 can be more uniformly cooled.

It is preferable that a rounded part are provided at a edge portion ofopening 15. Thus, the heat exchange gas easily flows into passages 16.Separating wall 19 separates adjacent openings 15. Then, it ispreferable that a thickness of separating wall 19 in a depth is biggerthan a thickness of separating wall 19 in the vertical direction. Bythis structure, the cross sectional area of passage 16 is made large,and also the strength of separator 12 can be made high.

It is preferable that binding bars 13 are respectively disposed at sidesurfaces of assembled battery 10. Preferably, binding bar 13 includesmain part 13 a, and bending parts 13 b formed at an upper end part and alower end part of main part 13 a respectively. Main part 13 a isdisposed so as to face the side surface of assembled battery 10. Bendingpart 13 b formed at the upper end part of main part 13, is disposed onthe upper surface of assembled battery 10. Bending part 13 b formed atthe lower end part of main part 13, is disposed on the lower surface ofassembled battery 10. Here, bending part 13 b may be provided only atthe upper end part of body part 13 a. In the structure where binding bar13 is disposed at the side surface of assembled battery 10, when bindingbar 13 is pressed to small area side surface 2 b of rectangular batterycell 1 from the outside, binding bar 13 may be deformed, and may contactsmall area side surface 2 b of rectangular battery cell 1. Then,normally, rectangular outer case 2 and binding bar 13 are made of metalrespectively. It is assumed that binding bar 13 contacts small area sidesurfaces of the plurality of rectangular battery cells 1, andrectangular outer cases 2 of the plurality of rectangular battery cells1 may be short-circuited through binding bar 13. In contrast, inassembled battery 10 relating to the embodiment, separator 12 has sidewall part 12 b and openings 15 at side wall part 12 b, and the heatexchange gas flows into passages 16 through openings 15. Thus, more areaof small area side surface 2 b of rectangular battery cell 1 can becovered with side wall part 12 b, while the heat exchange gas easilyflows into passage 16. Accordingly, cooling efficiency of rectangularbattery cell 1 is not decreased, and the short circuit by binding bar 13can be prevented, and then assembled battery having a high reliabilitycan be obtained. Here, it is preferable that a height of side wall part12 b of separator 12 is bigger than a high of small area side surface 2b of rectangular battery cell 1. Then, preferably, 60% or more in thearea of small area side surface 2 b of rectangular battery cell 1, morepreferably 70% or more is covered with side wall part 12 b of separator12. It is preferable that bending part 13 b of binding bar 13 isdisposed so as to contact separator 12.

As shown in FIG. 4, FIG. 11A, and FIG. 11B, it is preferable thatseparator 12 has bottom part 12 c. Bottom part 12 c is formed at thelower end of body part 12 a, so as to extend in the stacked direction ofrectangular battery cells 1. Bottom part 12 c is disposed so as to facebottom surface 2 c of rectangular battery cell 1. In the one surfaceside of body part 12 a, bottom part first region 12 c ₁ is provided atone side in the width direction of body part 12 a, and bottom partsecond region 12 c ₂ is provided at other side. As shown in FIG. 11B,bottom part first region 12 c ₁ is located slightly higher than bottompart second region 12 c ₂. In the stacked direction of the rectangularbattery cell 1, a distance L2 from body part 12 a to end part 12 e ₂ ofbottom part second region 12 c ₂, is larger than a distance L1 from bodypart 12 a to end part 12 e ₁ of bottom part first region 12 c ₁. Thus,in a state of the assembled battery, bottom part second region 12 c ₂ ofadjacent other separator is disposed at a lower surface side of bottompart first region 12 c ₁ such that bottom part first region 12 c ₁ ofthe one side separator 12 and bottom part second region 12 c ₂ of theother separator are overlapped each other. Also, bottom part firstregion 12 c ₁ of the adjacent other separator is disposed at an uppersurface side of bottom part second region 12 c ₂ such that bottom partsecond region 12 c ₂ of the one side separator 12 and bottom part firstregion 12 c ₁ of the other separator are overlapped each other. Thus,bottom parts 12 c of the adjacent separator are connected such that theyare fitted each other.

In this configuration, when water is formed by dew condensation or thelike on a floor surface where the assembled battery is mounted, dewcondensation water is prevented from intruding into the bottom surfaceside of rectangular battery cell 1 through a space between separators12. Therefore, rectangular outer case 2 of rectangular battery cell 1 isnot covered with insulation film or the like, and the short circuitbetween rectangular outer cases 2 of rectangular battery cell 1 by dewcondensation water, can be prevented. Here, in bottom part second region12 c ₂, ⅓ or more of the distance L2 from end part 12 e ₂ toward bodypart 12 a, more preferably 4/10 or more, is overlapped with bottom partfirst region 12 c ₁ of the other separator 12. Thus, dew condensationwater can be effectively prevented from intruding.

The end part of bottom part second region 12 c ₂ in the stackeddirection of the rectangular battery cells, has an inclined part 12 fwhere distances from body part 12 a gradually become small. Thus, sinceadjacent separators 12 are connected such that inclined parts 12 fcontact each other, assembling is carried out smoothly without catchingbetween them at a time of assembling the assembled battery. For example,when it is assumed that end part of body part 12 a extendsperpendicularly to body part 12 a without inclined part 12 f, bottomparts 12 c of separators 12 may catch each other at a time of assemblingthe assembled battery, and then assembling may not be carried outsmoothly.

As shown in FIG. 11A, preferably, separator part 12 c of separator 12has a point symmetrical shape in a plan view, with respect to a centerin the width direction of body part 12 a as center C of symmetry. At theone surface side of body part 12 a, bottom part first region 12 c ₁ andbottom part second region 12 c ₂ are formed. Also at the other surfaceside of body part 12 a, bottom part first region 12 c ₁ and bottom partsecond region 12 c ₂ are formed. Bottom part first region 12 c ₁ locatedat the one surface side of body part 12 a, faces bottom part secondregion 12 c ₂ located at the other surface side of body part 12 athrough body part 12 a. Also, bottom part second region 12 c ₂ locatedat the one surface side of body part 12 a, faces bottom part firstregion 12 c ₁ located at the other surface side of body part 12 athrough body part 12 a. Thus, bottom parts 12 c of adjacent separators12 are easily fitted each other.

As shown in FIG. 4, separator 12 has upper wall part 12 d at the upperend of body part 12 a. This upper wall part 12 d is disposed so as toface sealing plate 3 of rectangular battery cell 1. In upper wall part12 d, openings or a cut-out are provided at locations facing positiveterminal 4, negative terminal 5, and gas exhaust valve 8. However, inseparator 12, upper wall part 12 d may not exist or may not be providedat the location or the vicinity facing gas exhaust valve 8.

[Others]

Material of separator is not limited specifically, preferably haselectrical insulation property. Especially, it is preferable that it ismade of a resin. The separator is more preferably made of polybutyleneterephthalate (PBT), polyamide (PA), polycarbonate (PC), polypropylene(PP). When the rectangular outer case is made of metal, outer surfacesmay be covered with resin film or the like. Thus, in the presentinvention, it is not necessary that the small area side surface of therectangular outer case directly faces the side wall part of theseparator, and then the small area side surface of the rectangular outercase may face the side wall part of the separator through resin film. Atype of heat exchange gas is not limited specifically, it is preferableto use air. Instead of making cooling gas as heat exchange gas flow, bymaking hot gas flow through passages, rectangular battery cell 1 can beheated. In this case, according to the present invention, rectangularbattery cell 1 can efficiently be heated. It is more preferable that theassembled battery described above is used for a vehicle.

REFERENCE MARKS IN THE DRAWINGS

-   1: rectangular battery cell-   2: rectangular outer case-   2 a: large area side surface-   2 b: small area side surface-   2 c: bottom surface-   3: sealing plate-   4: positive terminal-   5: negative terminal-   6: insulation member-   7: insulation member-   8: gas exhaust valve-   9: sealing plug-   10: assembled battery-   11: end plate-   12: separator-   12 a: body part-   12 a ₁: vertical portion-   12 a ₂: horizontal portion-   12 b: side wall part-   12 b ₁: first region-   12 b ₂: second region-   12 c: bottom part-   12 c ₁: bottom part first region-   12 e ₁: end part-   12 c ₂: bottom part second region-   12 e ₂: end part upper wall part-   12 d: upper wall part-   12 f: inclined part-   13: bus-bar-   13 a: main part-   13 b: bending part-   13 c: opening-   14: bus-bar-   15: opening-   16: passage-   16 a: first passage-   16 b: second passage-   17: body part opening-   18: recess part-   19: separating wall-   20: projection part

1. An assembled battery comprising: a pair of end plates; and aplurality of rectangular battery cells stacked through separators,between the pair of the end plates, wherein each of the rectangularbattery cells has a bottom surface, a pair of large area side surfaces,and a small area side surface, each of the separators has a body partand a pair of side wall parts provided at both ends in a width directionof the body part, the body part is disposed between adjacent batterycells of the rectangular battery cells, The body part has verticalportions vertically extending in an alternating manner from above tobelow and a horizontal portion horizontally extending, and an end partof each of the vertical portions is connected to an end part of thehorizontal portion. a first passage where heat exchange gas passes, isformed between one surface of the body part of each of the separatorsand one adjacent battery cell of the rectangular battery cells, a secondpassage where heat exchange gas passes, is formed between other surfaceof the body part of each of the separators and other adjacent batterycell of the rectangular battery cells, the first passage and the secondpassage are provided in an alternating manner from above to below, theside wall parts of each of the separators are disposed so as to face thesmall area side surfaces of the adjacent two rectangular battery cells,each of the side wall parts has an opening, and at least one of thefirst passage and the second passage are exposed through the opening. 2.The assembled battery according to claim 1, wherein a plurality of theopenings are provided at each of the side wall parts, the plurality ofthe openings are arranged in a vertical direction, the first passage andthe second passage are exposed through the plurality of the openings. 3.The assembled battery according to claim 1, wherein a thickness of thehorizontal portion in a vertical direction is larger than a thickness ofone of the vertical portions in a horizontal direction.
 4. The assembledbattery according claim 1 wherein through one of the openings exposedare the small area side surface of the one adjacent battery cell locatedat a side of the one surface of the body part, and the small area sidesurface of the other adjacent battery cell at a side of the othersurface of the body part.
 5. The assembled battery according to claim 2,wherein through one of the openings exposed are the first passage andthe second passage, one of the openings through which the first passageis exposed, and one of the openings through which the second passage isexposed, are provided in an alternating manner from above to below. 6.The assembled battery according to claim 1, further comprising a bindingbar, wherein one end of the binding bar is connected to one of the pairof the end plates, and other end of the binding bar is connected toother of the pair of the end plates, and the binding bar is disposed ata side surface of the assembled battery.
 7. The assembled batteryaccording to claim 1, wherein each of the separators has a bottom partat a low end part of the main body, the bottom part is disposed so as toface the bottom surface of one of the rectangular battery cells, thebottom part at the side of the one surface of the body part, has abottom part first region and a bottom part second region, and the bottompart first region is located higher than the bottom part second region,the bottom part first region is disposed at an upper surface side of thebottom part second region in one adjacent separator of the separators,and the bottom part second region is disposed at a lower surface side ofthe bottom part first region in other adjacent separator of theseparators.
 8. The assembled battery according to claim 7, wherein adistance from the body part to an end part of the bottom part secondregion in a stacked direction of the rectangular battery cells, islarger than a distance from the body part to an end part of the bottompart first region in the stacked direction of the rectangular batterycells.
 9. The assembled battery according to claim 8, wherein the endpart of the bottom part second region in the stacked direction of therectangular battery cells, has an inclined part where distances from thebody part gradually become small.
 10. A vehicle comprising: theassembled battery according to claim
 1. 11. A vehicle comprising: theassembled battery according to claim
 2. 12. A vehicle comprising: theassembled battery according to claim 3.